Hyperbranched polyimide (HBPI) membranes have emerged as promising materials for gas separation due to their loose interchain structure and large free volume. However, their widespread application is hindered by challenges such as complex synthesis procedures, high-cost monomers, and poor resistance to plasticization. In this study, a series of Trimesoylchloride (TMC)-branched 6FDA-based PI membranes were successfully synthesized using different contents of TMC as a branching agent to regulate the pore distribution.The molecular structure and degree of branching (DB) of HBPI were characterized using FTIR and 1H NMR. The incorporation of TMC into the HBPI structure effectively enhanced the permeability and selectivity of the acyl chloride-branched PI membranes while improving thermal stability. The optimized membrane (A5-TMC content is 5%), exhibits the improving O2 and CO2 permeabilities of 176.52 and 930.94 Barrer combined with the O2/N2, CO2/N2 and CO2/CH4 selectivities of 4.68, 24.65 and 23.85, respectively. Particularly, the A5 HBPI membrane, with a DB value of 85.71%, demonstrated superior anti-aging properties compared to linear 6FDA-DAM membrane over 365 days. Most importantly, the 6FDA-DAM-TMC HBPI membranes significantly enhanced the resistance to plasticization at elevated CO2 feed pressures, maintaining stability up to 300 psi and significantly outperforming the linear 6FDA-DAM membrane. This study provides an effective method for the fabrication of high-performance gas-separated polymer membranes with enhanced plasticization resistance and long-term durability for advanced gas separation applications.

The introduction of long side chains into anion exchange membranes (AEMs) is a common strategy for improving OH- transport. However, the effect of different chemical structures of side-chain on OH- transport in poly(arylene indole piperidinium) AEMs remains unclear. This study investigates the effects of four distinct side-chain chemical structures in poly(arylene indole piperidinium) AEMs (specifically, all-carbon side chains (a-PITPC10), side chains with amino groups (a-PITPC7N3), side chains with ethoxy groups (a-PITPC7O3), and side chains with fluoro groups (a-PITPC10F21)) on OH- transport rates and mechanisms using molecular dynamics (MD) simulation methods. The simulation results show that the trend of OH- transport rate at the same hydration number is a-PITPC7N3 < a-PITPC10F21 < a-PITPC10 < a-PITPC7O3. The flexible side chains containing ether oxygen groups have a stronger ability to move, hence the segments have a higher degree of freedom of movement, which is beneficial to the construction of a favorable micro-morphology. At the same time, the cation-dipole interaction between the main chain cation and the ether oxygen group in the side chain of a-PITPC7O3 promotes the aggregation of nearby cationic groups, enlarging the overlapping area of the surrounding hydration shells, thereby facilitating the transport of OH-. Compared to a-PITPC10, in a-PITPC7N3, the strong hydrophilicity of the side chains causes water molecules to tend to disperse, and the bottleneck volume fraction occupied by ion transport channels is the largest, hindering OH- transport. Moreover, in a-PITPC10F21, the strongly hydrophobic side chains cause water molecules to aggregate excessively, forming wide ion transport channels, but their continuity is poor, which is not conducive to OH- transport. The flexible side chains in a-PITPC7O3 facilitate the uniform dispersion of water molecules in the system, forming continuous ion transport channels, which is conducive to improving OH- transport performance. Therefore, the poly(arylene indole piperidinium) AEM with ether oxygen groups (a-PITPC7O3) outperforms other side-chain structured AEMs (a-PITPC10, a-PITPC7N3, and a-PITPC10F21) in improving OH- transport.

The introduction of hydrophobic substances has a positive effect on the OH- transport of anion exchange membranes (AEMs). This study designs four fluorinated AEMs and investigates the effects of changes in the fluorinated structures on ion transport with molecular dynamics (MD) simulations. The simulation results indicate that the self-diffusion coefficient of OH- first increased and then decreased with increasing hydrophobicity at the same hydration number. As the hydrophobicity increases, the possibility of OH- dissociation from the cations within the AEMs gradually increases. However, the domain barriers resulting from excess hydrophobicity are not conducive to ion transport. In addition, increases in the hydrophobicity lead to increases and then decreases in the widths of the channels within the AEMs, while aggregation of adjacent cations within the intrachains facilitates OH(- )transport between the cations. Therefore, the introduction of fluorinated structures with moderate hydrophobicity into the main chain is an effective strategy for improving the AEMs.

Experimental studies have confirmed that introduction of the proper content of dibenzo-18-crown-6-ether (DE) into main-chain poly(arylene piperidinium) anion exchange membranes (AEMs) improved the efficiency of OH- transport. In this study, models of the AEMs (PDTP-x) were constructed with varying molar contents of DE groups (x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25). Molecular dynamics simulations were employed to investigate the microscopic effects of the DE groups on OH- transport. The analysis examined the impact of the volume of the overlapping hydration shells around piperidinium groups and the continuities and uniformities of the ion transport channels. Furthermore, the stabilities of the hydrogen bonds between water molecules explained the effect of x on OH- transport. The results showed that the total overlap volume initially increased and then decreased as x increased. When the content of DE groups was appropriate, the hydration shells of the cations exhibited considerable overlap, which facilitated the formation of continuous and uniform ion transport channels. Additionally, the stabilities of the water hydrogen bonds initially decreased and then increased as x increased. The stabilities of the hydrogen bonds were lowest when the DE content was optimal, which facilitated the transport of OH-.

Recently, the polymers of intrinsic microporosity (PIMs) exhibit good potential in high-temperature proton exchange membrane fuel cells (HT-PEMFCs) due to their tunable microporosity and functionality. In this paper, alkaline pyrrolidine and piperidine functional groups were introduced onto PIM-1 via the classical Mannich reaction obtaining PIM-1/PIM-Py-50 and PIM-1/PIM-MePi-50. It was found that, compared with commercial Meta-polybenzimidazole (m-PBI) membrane, PIMs membranes showed superior retention of phosphoric acid (PA) and conductivity due to their grafting alkaline groups and rich micropores. After equilibration under 80 °C/40% relative humidity (RH) for 150 h, the PA retention of PA doped PIM-1/PIM-Py-50 (PIM-1/PIM-Py-50/PA) and PA doped PIM-1/PIM-MePi-50 (PIM-1/PIM-MePi-50/PA) membranes were 74.13% and 68.52%, respectively, much higher than PA doped m-PBI (m-PBI/PA) (45.73%). PIMs membranes maintain excellent dimensional and conductivity stability at 160 °C operating conditions, e.g. PIM-1/PIM-Py-50/PA membrane showed area swelling retention and volume swelling retention of 84.69% and 82.19% after 230 h at 160 °C. In addition, with the similar PA uptake, PIMs membranes displayed higher conductivity and peak power density (PPD) at 160 °C. In the accelerated stress test (AST) the PPD of the fuel cell (FC) with the PIM-1/PIM-Py-50/PA membrane remained 81.25% after 200 aggressive start-up/shut-down cycles at 80 °C. Therefore, PIM-based membranes alkaline groups exhibit a wider temperature operating window, providing theoretical guidance for the design and study of the next generation of high-temperature proton exchange membranes (HT-PEMs).

This study employs the same diamine monomer to synthesize polyimide (PI) and Troger's Base-based polymers of intrinsic microporosity (TB), which exhibit infinite miscibility due to like-dissolves-like phenomenon. The TB and PI exhibit significantly different thermal decomposition temperatures, enabling the partial carbonization of TB at a lower temperature while retaining the favorable mechanical properties of PI. Consequentially, This work propose a novel method to prepare blend membranes with a partial amorphous carbon structure. These membranes have excellent gas separation performance, similar to that of carbon membranes, while also retaining the machinability of traditional polymer membranes. The molecular structure of the material is characterized using 1H NMR and FTIR spectra, while the microscopic morphology is observed through scanning electron microscopy. Molecular dynamics simulations confirm the compatibility of both polymers and explain the improved properties. Gas transportation measurement confirms that PI@TB blend membranes demonstrate significant improvement in gas separation performance compared to original membranes. Specifically, enhancements in the gas separation performance of CO2/CH4, H-2/CH4, and O-2/N-2 systems have been observed, with the CO2/CH4 pair demonstrating the most remarkable improvements, surpassing the 2019 Robeson upper limit. This design strategy can be applied to produce blend membranes containing amorphous carbon that exhibit great potential for high-performance separation processes in the future.

This study employs the same diamine monomer to synthesize polyimide (PI) and Tröger’s Base-based polymers of intrinsic microporosity (TB), which exhibit infinite miscibility due to like-dissolves-like phenomenon. The TB and PI exhibit significantly different thermal decomposition temperatures, enabling the partial carbonization of TB at a lower temperature while retaining the favorable mechanical properties of PI. Consequentially, This work propose a novel method to prepare amorphous carbon molecular sieve membranes with a partial amorphous carbon structure. These membranes have excellent gas separation performance, similar to that of carbon membranes, while also retaining the machinability and partial mechanical properties of traditional polymer membranes. The molecular structure of the material is characterized using 1H NMR and FTIR spectra, while the microscopic morphology is observed through scanning electron microscopy. Molecular dynamics simulations confirm the compatibility of both polymers and explain the improved properties. Gas transportation measurement confirms that PI@TB amorphous carbon molecular sieve membranes demonstrate significant improvement in gas separation performance compared to original membranes.Specifically, enhancements in the gas separation performance of CO2/CH4, H2/CH4, and O2/N2 systems have been observed, with the CO2/CH4 pair demonstrating the most remarkable improvements, surpassing the 2019 Robeson upper limit. This design strategy can be applied to produce amorphous carbon polymer membranes that exhibit great potential for high-performance separation processes in the future.

The introduction of different nonionic pendant groups in the backbones of polymeric anion exchange membrane (AEM) materials not only induces microphase separated morphology but also greatly impacts the other physicochemical properties of AEMs. Herein, we reported a series of poly-(biphenyl piperidinium) copolymers having different nonionic pendant groups on the backbones, including methyl, phenyl, and bromomethyl, which were derived from the ketone comonomers in the superacid-catalyzed polycondensation. Under similar ion exchange capacity, the PBP-M-35 membrane with methyl pendant groups shows the highest water uptake due to the less steric effect and electronic effect, reaching the highest OH- hydroxide conductivity (50.7 mS/cm at 20 C-degrees in liquid water) than other membranes. In addition to high conductivity, the PBP-M-35 membrane with more water absorption displayed superior alkaline stability, with the retention of a conductivity of 84.5% after 1200 h in 1 M KOH at 80 C-degrees. Consequently, the PBP-M-35 membrane presented a performance of 2000 mA/cm(2) at 1.8 V in a water electrolyzer (with the IrO2 anode and Pt/C cathode in 1 M KOH at 80 C-degrees). Further continuous operation under different conditions suggested that the cell with the PBP-B-30 membrane could operate under Ni-foam electrodes in 1 M KOH at 80 C-degrees for 240 h, and more harsh working conditions (6 M KOH at 80 C-degrees) led to the fast failure of the cell.

Blendingpoly-[2,2 '-(1,4-naphthalene)-5,5 '-benzimidazole](NPBI) with main chain-type N-spirocyclic quaternary ammonium ionenes(SI) could effectively improve the dimensional stability of anionexchange blend membranes (AEBMs), while the mechanism of the effecton OH- transport has not been elucidated. In thiswork, the effect of the NPBI content and deprotonation degree on OH- transport was revealed by molecular dynamics simulation.The simulation results showed that the free water content increasedwith increasing NPBI content at the same NPBI deprotonation degree,which facilitated the OH- transport. However, thedecreased distance between adjacent N-spirocyclic quaternary ammoniumcations (NSQAs) in the interchain and the increased correlation betweenOH(-) were detrimental to OH- transport.These resulted in AEBMs with 20 wt % NPBI content exhibiting the bestOH(-) transport. When the NPBI content was 20 wt %,the distance between adjacent NSQAs in the interchain increased andOH(-) was more dispersed in the aqueous phase withdecreasing NPBI deprotonation degrees, leading to the increased OH- transport. Because of the "trade-off"effect between the OH- transport and dimensionalstability of AEBMs, we suggest that AEBMs with 20 wt % NPBI contentand 50% NPBI deprotonation degree (SI/NP-50-20) can be selected tobalance OH- transport and dimensional stability.This work will provide further guidance for the design of blend modificationof AEBMs.

The macromolecular crosslinkers of bromomethylated polymer of intrinsic microporosity (PIM-BM) are successfully introduced into the poly(2,2'-(1,4-naphthalene)-5,5 '-bibenzimidazole) (NPBI) to improve the phosphoric acid retention in high temperature proton exchange membrane fuel cell (HT-PEMFC). Thanks to the excellent miscibility between two polymers, the transparent and tough crosslinked membranes (NPBI/PIM-BM-x) have been obtained by the solution-casting. Compared with pristine NPBI membrane, the crosslinked membranes exhibit higher retention of phosphoric acid (PA) in various complicated temperature/humidity conditions due to the microporosity resulting from the micropore polymer of intrinsic microporosity (PIM) crosslinker. Specifically, the PA doped NPBI/PIM-BM-15 (NPBI/PIM-BM-15/PA) membrane shows 57.73% PA retention under 80 degrees C/40% relative humidity (RH), higher than PA doped NPBI (NPBI/PA) membrane (48.12%). Therefore, under accelerate stress test (AST) in fuel cells, the crosslinked NPBI/PIM-BM-15/PA membrane shows an excellent retention of peak power density, e.g. remaining 88.99% after 200 cycles of testing at 80 degrees C. This value is much better than pristine NPBI based fuel cell (only remaining 52.01% after 200 cycles under the same testing conditions). At a higher temperature of 160 degrees C without extra humidity, the fuel cells based on PA doped crosslinked membranes show comparable peak power density of 565-627.5 mW cm(-2) to NPBI (632.5 mW cm(-2)) without an obvious sacrificing of initial fuel cell performance. Thus, the improved PA retention of the HT-PEM based on with PIMs crosslinker shows a great potential to broaden the operational temperature range and to be used for the nextgeneration HT-PEMs.

The introduction of long side chains to improve hydroxide transport in anion exchange membranes (AEMs) is a common strategy. However, the mechanism of the effect of side-chain position on hydroxide transport in the currently emerging poly(arylene indole piperidinium) AEMs remains unclear. Molecular dynamics simulation was performed to investigate the effect of the side-chain position on hydroxide transport. Three typical long side-chain poly(arylene indole piperidinium) AEMs were constructed, which were tadpole-chain type (t-PITPC10), pendant-chain type (p-PITPC10), and side chains attached onto the backbone separated from cationic groups type (a-PITPC10). The simulation results suggest that the self-diffusion coefficients of hydroxide follow the order: t-PITPC10 < p-PITPC10 < a-PITPC10 at the same hydration number. The strong interaction between the hydrophobic indole groups and hydroxides in t-PITPC10 and p-PITPC10 hinders the efficient transport of hydroxide. In contrast, this interaction is weaker in a-PITPC10 due to side chains being connected at indole groups. The overlapping region of the hydration shell around adjacent cationic groups is larger in a-PITPC10. Meanwhile, the connected aqueous phase and ion transport channels in a-PITPC10 promote hydroxide transport. Hence, the AEM with side chains attached onto the backbone separated from cationic groups (a-PITPC10) is superior to the AEMs with side chains linked to cationic groups (t-PITPC10 and p-PITPC10) in the improvement of hydroxide transport.

Molecular dynamics (MD) and density functional theory (DFT) were utilized to evaluate the effect of deprotonation degree and flexibility of polybenzimidazole (PBI) on the inhibiting water uptake mechanism of main chain type N-spirocyclic quaternary ammonium ionene (SI) as anion exchange membranes (AEMs). Results show that the electrostatic interactions play a key role in inhibiting water uptake of the blend membranes, which is mainly originated from the N+ of SI and the N- of deprotonated PBI and partly from the inter-molecular weak hydrogen bonding C-H center dot & nbsp;center dot & nbsp;center dot & nbsp;N and C-H center dot & nbsp;center dot & nbsp;center dot & nbsp;pi The E-ele between SI and PBI of SI/NP-50 and SI/NP-100 increases by 745.6% and 1291.8% compared with SI/NP-0 at lambda=40, respectively, which exhibits the PBI deprotonation enhances the electrostatic interactions. And the E-ele between SI and PBI increases as the flexibility of PBI decreases. Furthermore, the pi-pi stacking interactions contribute to the inhibiting water uptake of SI AEMs. The AEM of SI blended with low flexible poly[2,2'-(1,4-naphthalene)-5,5';-bibenzimidazoles] (NPBI) exhibits excellent dimensional stability due to strong electrostatic interactions. Our work deepens the understanding of the inhibiting water uptake mechanism of SI blended with PBI as AEMs from a microscopic viewpoint, and provides guidance for the selection of PBI structure.

采用可逆加成-断裂链转移(RAFT)分散聚合法制备了一系列固载L-脯氨酸、CO2响应性结构单元甲基丙烯酸二乙氨基乙酯(DEA)含量不同的mPEG22-b-P[BnMAx-co-L-ProlAn]-b-PDEAyPBL-b-PD-(DEA)m(m=0,1,2,3)和单体序列结构不同的mPEG22-b-P(L-ProlA)-b-P[BnMA-co-DEA](PL-b-PBD)聚合物.利用核磁共振氢谱(1H NMR)、X射线光电子能谱(XPS)和凝胶渗透色谱(GPC)对聚合物的化学结构及相对分子量分布进行了表征.采用动态光散射(DLS)对聚合物的自组装行为及形成纳米反应器后的CO2响应性进行了研究.同时,结合耗散粒子动力学(DPD)模拟探究了聚合物亲疏水单体比例和序列结构对聚合物自组装结构的影响.最后,将制备的纳米反应器用于水相催化直接不对称Aldol反应,结果表明,PBL-b-PD-(DEA)2具有最佳的催化性能[96％conv.,93/7(anti/syn),94％ee].该研究为探究聚合物自组装结构对其催化性能的影响提供了新思路.

Imidazolium-based groups are promising organic cations in anion exchange membrane (AEM) materials. To investigate the effect of the imidazolium structure on OH- transport and alkaline stability of AEMs, we performed molecular dynamics simulation studies on hydrated poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) AEMs with imidazoliums modified by various substituents and/or alkyl pendent/spacer chains. Imidazoliums with the methyl or phenyl substituent at the C2, C4, and C5 sites or alkyl pendant chains at the N3 site show a steric effect on the distribution of water and OH- around imidazoliums, which inhibits the OH- transport but increases the alkaline stability of AEMs. By introducing alkyl spacer chains, the enhanced hydration structure of imidazolium promotes OH- transport, but the weakened steric effect of PPO on imidazolium decreases alkaline stability. We elucidate that the PPO AEMs modified by 1,2,4,5-tetramethylimidazolium and alkyl spacer chains with six or eight aliphatic carbons show good balance between OH- transport and alkaline stability of AEMs. Moreover, the complete hydration shells of both imidazolium and OH- enhance the OH- transport efficiency and decrease the possibility of imidazolium degradation with the hydration level more than six. Our work provides a design principle of imidazolium-based AEMs in fuel cell applications.

To produce anion exchange membranes (AEMs) possessing high conductivity and chemical stability, we propose a ternary copolymerization strategy to prepare comb-shaped poly(arylene indole piperidinium) copolymers with different lengths of side chain by the design of alkyl-functionalized isatin comonomers in the acid-catalyzed Friedel-Crafts polycondensations of N-methyl-4-piperidone and p-terphenyl. These polymers have a characteristic feature of hydrophobic side chain separately attached onto aryl-ether free backbones to induce microphase separated morphology and stable piperidinium cation within the backbone to ensure the alkaline stability. PITPC10Q85 membrane with C10 side chain showed the highest hydroxide conductivity of 134.5 mS/cm at 80 degrees C due to the formed microphase separated morphology. Alkaline stability testing in 1 M NaOH at 80 degrees C demonstrated that 80% of initial conductivity was retained for PITP-C10Q85 membrane after 1200 h of testing, owning to the chemical degradation of piperidinium cation in comb-shaped membranes via Hoffman elimination and nucleophilic substitution reaction. By assembling in alkaline fuel cells, PITP-C10Q85 membrane delivered a peak power density of 445 mW/cm(2) at a current density of 870 mA/cm(2) at 60 degrees C. Meanwhile, in-situ stability of PITPC10Q85 membrane demonstrated a voltage decay rate of 3.67 mV/h over 75 h of operating at 300 mA/cm(2), and post-cell analysis of the aged membrane revealed that predominant nucleophilic substitution reaction was found for the degradation of PITP-C10Q85 membrane, being different from the degradation mechanisms in the ex-situ stability tests. The above results manifested that regulating the alkyl side chains on the backbone directly is a promising strategy to achieve high performance AEMs with favorable morphology, high conductivity and alkaline fuel cell performance.

A series of polymer based on spirocyclic quaternary ammonium (QA) cations having 5-/6- and 6-/6- membered rings were designed and prepared from tetrakis(bromomethyl) monomers to investigate the alkaline and fuel cell stability of spirocyclic ionenes. The alkaline stability testing of model compounds and DFT calculations showed that the spirocyclic QA having 5-/6-membered rings based on phenyl and biphenyl showed a better stability than that of the spirocyclic QA with naphthalene 6-/6-membered rings probably due to the strong electrowithdrawing effect of naphthalene rings. Although the high molecular weight polymer with naphthalene rings could not be obtained, the spirocyclic ionenes based on phenyl or biphenyl showed high molecular weight. Thus, the blending membrane with rigid NPBI have been fabricated to mitigate the water solubility of spirocyclic ionenes due to their high IEC values. The blending membrane showed a high ionic conductivity even at elevated temperature without any excessive swelling in spite of its high IEC value. Employing the spirocyclic ionenes as membrane, the H-2/O-2 single cell at 60 degrees C was firstly demonstrated. A peak power density of 135 mW cm(-2) was achieved for PP80N20 membrane. Surprisingly, the fuel cell device durability provided a counterintuitive data that showed that spirocyclic ionenes with excellent alkaline stability were not superior in device function assessment. A rapid ring-opening degradation as confirmed by NMR technique for the spirocyclic ionenes was observed in device testing. These results that stability investigation gives us new directions for polymer and cations designs for highly durable devices.

Quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) copolymers featuring pendant sterically-protected imidazolium groups are presented as new anion exchange membranes (AEMs) for alkaline fuel cell application. Four kinds of imidazoliums, in which the substitutions were located at different positions in imidazolium rings, were grafted on the PPO backbones for systematically assessing structure-property relationship in the resulting imidazolium-based AEMs. Grafting imidazoliums with less substitutions leads to high water uptake as well as sufficient ionic conductivity. The 1,2,4,5-tetramethylimidazolium-functionalized PPO AEM (PPO-TMIm) showed the higher water uptake (53.2 wt%) and hydroxide conductivity (31.7 mS/cm) at room temperature in comparison to the AEM (PPO-TPIm) having sterically-protected 2-(2,4,6-trimethyl)phenyl-4,5-diphenyl-1methyl- imidazolium. With increasing steric hindrance in the positions of imidazolium rings, PPO-TPIm AEM exhibited superior alkaline stability. After 192 h of immersion in 1 M NaOH at 80 degrees C, PPO-TPIm membrane retained 86.7% of the ionic conductivity with no obvious structure change as evidenced by H-1 NMR spectroscopy, while dealkylation degradation was observed for AEMs having 1,2,4,5-tetramethylimidazolium and 2-(2,6-dimethyl)phenyl-1-methyl-benzimidazoliums with 16.93% and 19.76% retention of conductivity. Furthermore, these imidazolium-based PPO copolymers were utilized as both polymer electrolyte membranes and ionomers in the membrane electrode assemble for alkaline fuel cell application. A single H-2/O-2 fuel cell testing showed that high peak power density of 128 mA/cm(2) at 60 degrees C was obtained for PPO-TMIm copolymer as an AEM, probably due to its high ion conductivity and comparable alkaline stability. However, under the same conditions, PPO-TPIm copolymer with the highest alkaline stability failed to be a separator in cells, and only 22.1 mW/cm(2) of peak power density was achieved as an ionomer in fuel cells. These results highlight that both ionic conductivity and alkaline stability of anion conductive polymers are important for fuel cell application as membranes and ionomers.

Thermal and magnetic dual-responsive c-proline nanohybrids (c-Pro-based-TMNHs) were prepared by grafting thermal-responsive thiol-terminated P(NIPAM co-L-ProlA)-b-POEGA-SH (PNLPO-SH) to vinyl-functionalized Fe3O4@SiO2-MPS through the thiol-ene click chemistry. The catalytic activity, selectivity and recyclability of LPro-based-TMNHs were evaluated in a model asymmetric aldol reaction of cyclohexanone and 4-nitrobenzaldehyde in water. Thermal responsiveness of the L-Pro-based-TMNHs induced self-assembly to produce a hydrophobic microenvironment in aqueous medium for catalyzing asymmetric aldol reaction. The catalytic performance can be tuned by the molar ratio of PNLPO-SH to Fe3O4@SiO2-MPS, and L-Pro-based-TMNHs-2 with a ratio of 1:6 exhibited best catalytic activity and selectivity. At 50 degrees C and 5 mol% catalyst loading, 94% cony., 81/19 anti/syn and 95% ee were obtained. On the other hand, magnetic responsiveness of the L-Pro-based-TMNHs facilitates catalyst separation and reuse in the presence of an external magnetic field, and these results indicated no loss of both catalytic activity and selectivity associated with the course of recycling.

pH-Responsive copolymers with reversible transformation ability have been investigated as new effective carriers for L-proline to catalyze asymmetric aldol reaction in water. A series of block copolymers of mPEG-b-P (DEA(x)-co-L-ProlA(y)) (mPEG-PDL) bearing L-proline catalytic sites and pH-responsive poly (diethylaminoethyl methacrylate) (PDEA) segments were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of methyl polyethylene glycol (mPEG) trithiocarbonate macro-RAFT agent. The pH-induced self-assembly behaviors of three copolymer catalysts with different contents of PDEA were investigated via the combination of UV-visible spectrometer (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM). Catalytic activity and stereoselectivity of these copolymer catalysts were evaluated by direct asymmetric aldol reaction of p-nitrobenzaldehyde and cyclohexanone in water. The results indicated that catalytic activity and stereoselectivity effected by the pH value of aqueous solution and the structures of copolymer catalyst assemblies. mPEG-PDL-2 give the aldol product with high cony., yield, anti/syn, and ee (92%, 91%, 92/8, 96%), respectively at pH 7.0. Furthermore, these pH-responsive copolymers supported L-proline are easily recycled by a reversible phase transition.

To realize highly stable anion exchange membrane for alkaline fuel cells, aryl-ether free polystyrene (PS) was employed as polymer backbone and functionalized with alkaline stable N-cyclic quaternary ammonium (QA), e.g. six-membered (DMP) and bis-six-membered N-cyclic QA (ASU) cations via "click chemistry". Surprisingly, aryl-ether free PS backbone having ASU cation displayed excellent chemical resistance in 1M NaOH CD3OD/D2O solution at 80 degrees C even for 3000 h without obvious degradation, as confirmed by NMR spectroscopy. After blending with poly(styrene-ethylene-co-butylene-styrene) (SEBS) copolymer which improved the film-forming ability due to the poor mechanical properties of PS, the ASU-based blended membrane (SEBS/PS-ASU) having SEBS polymer of 10 wt% possessed the hydroxide conductivity of 31.6 mS/cm with an ion exchange capacity (IEC) of 1.76 meq./g. This value was higher than the blended membrane having DMP cations (25.8 mS/cm with a IEC of 1.92 meq./g). Similar behavior has been observed for the PPO system having the same functional cations. It was believed that the high water uptake of ASU-based membrane resulted in the higher ion conductivity. Remarkably, 92.4% of initial hydroxide conductivity was retained for SEBS/PS-ASU membrane with aryl-ether free PS backbone after storage in 1M NaOH at 80 degrees C for 900 h, indicating the higher alkaline stability over the AEM counterpart with aromatic PPO polymer backbones having aryl ether bonds (21.0% retention in conductivity under the same test conditions). And the accelerated stability test in 5M NaOH at 80 degrees C demonstrated that only 16.8% of loss in conductivity was observed after 1800 h of testing for the blend AEMs having ASU cations. Furthermore, as ionomers in catalyst layers, the ASU-functionalized PS copolymers showed a peak power density of 130 mW/cm(2) at a current density of 210 mA/cm(2).